What are the most common statistical tests used in a diagnostic study Flashcards
Accuracy of the test in identifying the proportion of the people with the disease who have a positive test result
Sensitivity
Accuracy of the test in identifying the proportion of the people without the disease who have a negative test result
Specificity
How do you calculate sensitivity?
TP/(TP+FN)
How do you calculate specificity?
TN/(TN+FP)
If a test has moderate to high specificity, when the test is positive, it rules…
in the condition
If a test has moderate to high sensitivity, when the test is negative, it rules…
out the condition
How much more likely is a positive test (TP and FP) to be found in an individual with the disease (TP) than in a person without it (FP)?
Positive likelihood ratio
How do you calculate positive likelihood ratios?
Sensitivity/(1-specificity)
How much more likely is a negative test (TN and FN) to be found in an individual without the disease (TN) than in a person with it (FN)
Negative likelihood ratio
How do you calculate negative likelihood ratios?
(1-sensitivity)/specificity
Percentage of those with a positive test (TP and FP) that were actually reference standard positive (TP)
Positive predictive value
Percentage of those with a negative test (TN and FN) that were actually reference standard negative (TN)
Negative predictive value
How do you calculate positive predictive value?
TP/(TP+FP)
How do you calculate negative predictive value?
TN/(TN+FN)
How do you calculate prevalence?
(TP+FN)/(TP+FP+FN+TN)
